Fixing flaky test case in BulkDecompressor.java

[mihirgune]

Description

This Pull Request is meant to fix flakiness in the test BulkDecompressorTest.testDecompressUnknownCompressionFile()

The provided test is intermittently failing because it is doing a direct String comparison, in which the elements of a set are being printed in an error message. Since the order of the elements in a set is non-deterministic, the expected String is not matching the actual String. The following code is inducing the flakiness, where the BulkDecomopressor.SUPPORTED_COMPRESSIONS is a Set of supported compression types.

assertThat(
                  kv.getValue(),
                  containsString(
                      String.format(
                          BulkDecompressor.UNCOMPRESSED_ERROR_MSG,
                          unknownCompressionFile.toString(),
                          BulkDecompressor.SUPPORTED_COMPRESSIONS)));

The described issue can be reproduced by running the test using the nondex plugin, with the following command -

mvn -pl v1 edu.illinois:nondex-maven-plugin:2.1.7:nondex -Dtest="com.google.cloud.teleport.templates.BulkDecompressorTest"

which occasionally throws the error -

[ERROR] Failures: 
[ERROR]   BulkDecompressorTest.testDecompressUnknownCompressionFile:237 Decompress.out1: 
Expected: a string containing "Skipping file <sample_filename> because it did not match any compression mode ([SNAPPY, ZSTD, ZIP, BZIP2, LZO, DEFLATE, LZOP, GZIP])"
     but: was "Skipping file <sample_filename> because it did not match any compression mode ([GZIP, DEFLATE, LZO, ZIP, ZSTD, SNAPPY, LZOP, BZIP2])"

Fix

The provided fix changes the type of the SUPPORTED_COMPRESSIONS from java.util.Set to java.util.List. Since the set has been converted into a list, the ordering of the elements is deterministic, and hence the flakiness has been removed.

I'd love to get feedback on this pull request. Please let me know if you'd like to see any changes!

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 45.09%. Comparing base (e71280a) to head (528504d).
Report is 7 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #1986      +/-   ##
============================================
- Coverage     45.10%   45.09%   -0.02%     
+ Complexity     3614     3611       -3     
============================================
  Files           835      835              
  Lines         49739    49739              
  Branches       5240     5240              
============================================
- Hits          22437    22432       -5     
- Misses        25634    25638       +4     
- Partials       1668     1669       +1     

Components	Coverage Δ
spanner-templates	66.24% <ø> (-0.02%)	⬇️
spanner-import-export	64.16% <ø> (-0.05%)	⬇️
spanner-live-forward-migration	76.11% <ø> (ø)
spanner-live-reverse-replication	76.48% <ø> (ø)
spanner-bulk-migration	85.50% <ø> (ø)

Files with missing lines	Coverage Δ
...gle/cloud/teleport/templates/BulkDecompressor.java	56.96% <100.00%> (ø)

... and 3 files with indirect coverage changes